The environmental costs of mitigating energy poverty: Evidence from heavy metal contamination in BRICS urban rivers

• Seasonal monitoring revealed peak heavy metal levels during spring runoff. • Cr, Pb, and Cd were dominant pollutants across all sampling periods. • Bioaccumulation data indicated ecological risks to benthic organisms. • Industrial and vehicular sources were major contributors to contamination. • Multi-index assessment enhanced accuracy of ecological risk evaluation. This study investigates the degree of heavy metal contamination, ecological risks, and their socioeconomic linkages with energy poverty in urban river sediments across BRICS countries (Brazil, Russia, India, China, and South Africa). Through a comprehensive application of pollution indices, ecological risk assessment models, and multivariate statistical analyses, the following key conclusions were drawn: First, severe heavy metal pollution was observed. Significant contamination was identified in urban industrial zones, with particularly pronounced levels in the Economic and Technological Development Zone (ETDZ) in Zhongshan, China. Second, elevated ecological risks were evident. The ecological risk levels were predominantly classified as ‘high’ or above. Third, distinct socioeconomic driving factors were identified. Pollution hotspots exhibited strong correlations with industrialized regions and energy-poverty areas, while significant inter-metal correlations revealed complex pollution pathways resulting from the combined effects of industrial emissions and urban river systems. Fourth, seasonal variations were detected. Heavy metal pollution intensified during spring and summer in ETDZ, attributable to increased runoff and industrial discharges. This study provides a theoretical foundation for policymakers in emerging economies working at the intersection of energy poverty, ecological risks, and environmental resilience.